A secondary battery is repeatedly charged and discharged. For instance, a secondary battery mounted in a hybrid vehicle or an electric vehicle is charged and discharged with a large current (high-rate charge/discharge). Therefore, a nonaqueous electrolyte type lithium ion battery having a high energy density and a superior high-rate charge and discharge property has been developed for use in a vehicle. However, it is known that even the nonaqueous electrolyte type lithium ion secondary battery increases in internal resistance due to repeated charge and discharge with a large current (e.g., Patent Literature 1).
A nonaqueous electrolyte type lithium ion secondary battery arranged to restrain such an increase in internal resistance is disclosed in Patent Literature 1. In Patent Literature 1, a conductive layer is placed between an electrode current collector and an electrode material mixture layer to prevent deterioration of an electrode body. Accordingly, the nonaqueous electrolyte type lithium ion secondary battery restrains a decrease in voltage.